Piston ring expander



, m SA BF X .R G N .1 R w T s I P March 24, 1936.

Original Filed Fb. 15, 1933 Reissued Mar. 24, 1936 PISTON RING EXPANDER Frank A. Krebs, Brooklyn, N. Y., assignor to The Perfect Circle Company, Hagerstown, ImL, a corporation of Indiana Original No. 1,961,001, dated May 29, 1934, Serial This invention relates to improvements in piston ring expanders and has for an object the provision of a piston ring expander which is simple in design, inexpensive in construction, and efiicient and durable in use. A further object is the provision of a piston ring expander which may be inserted with facility behind worn or leaking piston rings for the purpose of augmenting the inherent expanding force of the ring, thus No 656,916, February 15, 1933. reissue March 1, 1935, Serial No. 8,931

7 18 Claims. (01.309-43) Application for Fig. 1, reference character In designates the piston of an internal combustion engine which operates in a bore of the cylinder I l. The piston is provided with peripheral grooves into which are fitted the piston rings l2 which possess an inherent expanding force causing the outer faces of the rings to bear against the cylinder wall. The rings I2 may consist of whole rings or of ring portions as is understood in the art. The lowering an expanding circumferential pressure on to prevent leakage past the ring. A further obmost ring is broken away' to show an expander ject is the provision of a piston ring expander ring in the groove and operative to exert circumwhich may be utilized with an out of round ferential pressure on the ring whereby to augcylinder to force the ring into non-leaking enment its inherent expanding force. gagement therewith. A further object is the The expander as shown in detail in Figs. 2, 3 provision of a piston ring expander which may and 5 comprises a carrier band l5 of relatively be utilized with lighter rings than ordinarily in soft and pliable metal, the band being in width use at the present time, with the expander furthe full width of the ring grooves into which it is nishing the additional expanding force necessary to, be inserted. In length the band l5 will vary upon lightening of the ring. A further. object is for different bore pistons with which it is to be 0 the provision of a piston ring expander having associated, it being understood that the band is improved design and constructional features. A usually designed to extend substantially throughfurther object is the provision of a piston ring out the circumference of the piston groove. expander comprising a plurality of spring ele- Along the length of the band are provided pairs ments adapted. to exert pressure circumferentially of opposed ears l6, preferably formed integrally 5 on the ring, and a carrier for said elements, with with the band, the said ears being adapted to be v the spring elements and the carrier so associated bent at right angles to the band proper. In orthat the possibility of separation or breakage o der that the outer faces of the ears l6 extend flush said parts is substantially eliminated. with the longitudinal edges of the band, the band Other objects will be in part obvious and in is slightly undercut at the base of the ears, as at part hereinafter pointed out in connection with ll, whereby, upon bending, the ears are fully 30 the following analysis of this invention, wherein encompassed within the width of the band. is illustrated one of the various possible embodi- Associated with the band is a plurality of spring monts of the present invention, together with steel leaves 20, approximately an inch long, certain modifications m detail. although this may vary somewhat, and of a width In the drawing to conform to the width of the ring groove. By 35 Fig. 1 is an elevation, partly in section, of a reference to Fig. 2, it will be noted that the spring piston provided with rings behind one of which is leaves are provided, intermediate their ends, with shown the expander in accordance with my inopposed notches 2|. The spring elements are vention; properly related with the band by superimposing 4o 0 Fig. 2 is a separated detail of the expander elethe leaves in overlying relation on the band so ments; that the ears l6 of the band extend through Fig. 3 is a partial edge view of the expander; notches 2|. Thereafter the ears l6 are bent over Fig. 4 is a top view of the expander associated the leaves, as more clearly indicated in Figs. 3 in the groove behind the ringf and 5. By such an arrangement the leaves are 5 Fig. 5 is a section through the expander on lines securely locked to the band l5, with the ears l6 5-5 of Fig. 4; interfitting the notches 2| and serving to prevent Fig. 6 illustrates in section a modified form of longitudinal movement of the elements in relation connection between the expander elements; to each other.

Fig. 7 is a plan view of a further modified form The end portions 22 of the spring leaves are of my invention; bent or curved or ground so that such portions, 50

Fig. 8 is a detail in section of the modified which engage the inner peripheral surface of the expander illustrated in Fig. 7; and piston ring, may. slide freely thereagainst. In

Fig. 9 shows a modified form of spring element Fig. 4 the expander is shown as seated in the pisfor use with a double piston ring. ton groove behind the piston ring l2 and exert- 55 Referring to the drawing, and particularly to said ring. The soft metal, flexible ring l5 easily adapts itself to circular formation within the groove, and each of the spring elements 20 exerts an independent expanding force against the rear face of the ring. with the curved end portions 22 of the leaves bearing against the ring in such manner that they may readily flex and slide against the ring. Accordingly, a uniform expanding pressure is exerted by the plurality of spring elements, the independent action of the leaves serving, however, to cause proper contact between a portion of the ring and an adjacent "out of round portion of the cylinder bore.

Among the advantages of the above described ear and notch connection may be noted the fol-- lowing. First, each spring leaf 20 has complete freedom of action and thus strain, either on the leaf itself or which might occur at the joint bee tween the leaf and its carrier band, is substantially eliminated. Secondly, in cases where the cylinders are worn badly, under which condition the piston receives a terrific blow at explosion,

the aforesaid type of joint permits the spring leaves to cushion the piston as it raps against the ears I6, which in turn stops the piston from hitting the. cylinder wall. Excessive cylinder wear and piston slap is thus prevented. Further, breakage of the spring leaves is also substantially eliminated.

The expander as above described, when used in conjunction with a slotted oil ring. may be provided with means to permit oil that passes behind the ring to drain back into the crank case.

1 Such draining means may comprise notches I8 along the edge of the carrier band, or, alternately, the carrier band l5 may be apertured as at I9 ,at intervals along its length, as indicated in Fig. 2.

In Fig. 6 I have shown a modified form of connection between the spring leaves and carrier band. According to such modification, the carrier band l5a, instead of having integral cars, is provided with notches 25 registering with notches 2!, of the spring leaves.- A clip 26 may pass under the carrier band and extends through notches 25, 2| of the band lid and spring leaves 20, respectively, the ends of the clip or connecting band being bent over on the spring leaves whereby to secure the latter to the band.

In Fig. 8 I have shown a further form of connection between a carrier band I51; and spring leaves 201;. According to such modified construetion, the carrier band lib is made as usual of a width which corresponds to the full width of the ring groove. Along its length the band is provided with pairs of apertures 28 which of course do not extend across the full width of the band. Through such a pair of apertures 28 is threaded a spring-steel leaf, the said leaf having both its ends bent or curved as heretofore, but having its intermediate portion substantially depressed. Thus when the leaves are properly associated with the band, as indicated in Fig. 8, the intermediate portion of the leaf bears against the bottom wall of the ring groove with the curved end portions sliding against the inner face of the piston ring. In this modified form the spring leaf, being substantially the width of the apertures 28, is of lesser width than the band and accordingly of lesser depth than the ring groove.

This latter described form'of connection, as with the previous forms, permits the leaves to flex independently of the carrier band and in such manner that the strains of explosion are taken up gradually and do not tend to break the spring or separate the same from the band.

In Fig. 9, I have illustrated a further, modification in the construction of the spring leaves of the type shown in Figs. 2 and 3. According to such modified structure, the spring leaf 200 is provided with tapered ends 22c curved as heretofore described. This type of leaf is advantageously used with a double piston ring. The tapered ends 220 act to separate the two rings, forcing one against the top and the other against the bottom of the ring groove. Such arrangement prevents oil from passing around the ring and stops what is known as blow-by or oil pumpmg.

Without further analysis, the foregoing will so fully reveal the gist of this invention that others can be applying current knowledge readily adapt it for various applications without omitting certain features that, from the standpoint of the prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention, and therefore such adaptations should and are intended to be comprehended within the meaning and range of equivalency of the following claims.

I claim:

1. A piston ring expander comprising a carrier band of soft. pliable metal, a plurality of spring steel leaves overlying the band, the leaves being formed with opposed edge notches intermediate the ends thereof, and means operatively related to said band and extending, through the notches for securing the leaves to the band.

2. A piston ring expander comprising a carrier band of soft, pliable metal, a plurality of spring steel leaves overlying the band, the leaves being formed with opposed edge notches intermediate the ends thereof, and the band having ears projecting therefrom to extend through the notches and over the leaves.

3. A piston ring expander comprising a carrier.

jecting therefrom to extend through the notches and over the leaves, the ends of the leaves being bent along a curvature.

'4. A piston ring expander comprising a carrier band of soft, pliable metal, a plurality of spring steel leaves overlying the band, the leaves being formed with opposed edge notches intermediate the ends thereof, the band and the leaves being provided with edge notches in registry, and an attaching clip extending through said notches and about the band and leaves for securing the latter to the band.

5. A piston ring expander comprising a. carrier band of soft, pliable metal, a plurality of spring steel leaves overlying the band, the leaves being formed with opposed edge notches intermediate the ends thereof, the band and the leaves being provided with edge notches in registry, and an its length, and spring leaves each threaded portion of the leaf disposed on one side of the band and the end portions of the other 8. A piston ring expander comprising a band having pairs of apertures arranged therein along its length, and spring leaves each threaded through a pair of apertures with the intermediate portion of the leaf disposed on one side of the band and the end portions on the other, and said end portions being curved.

9. A piston ring'expander comprising a carrier band of soft, pliable metal, a plurality of spring steel leaves overlying the band, the leaves being formed with opposed edge notches intermediate the ends thereof, the band having ears projecting therefrom to extend through the notches and over the leaves, and the ends of the leaves being tapered.

10. A piston ring expander adapted to be placed in a piston ring groove behind a piston ring and comprising a carrier band of thin, soft, pliable metal having an axial width substantially equal to that of said piston ring groove, a plurality of spring steel leaves having'at least the major portion of their length in overlying substantially concentric relation to said carrier band, and means within the confines of the width of said carrier band connecting the middle portion of said leaves to said carrier band, the end portions of said leaves extending in opposite directions from said connecting means and being adapted to engage the inner periphery of a piston ring.

11. A piston ring expander comprising 'a carrier band, a plurality of spring leaves overlying the band, the leaves being provided with opposed edge notches intermediate the ends thereof, and the band having ears projecting therefrom and extending through said notches and over the leaves for securing the latter to the band.

12. A piston ring expander comprising a carrier band, a plurality of spring leaves overlying the band, the leaves being provided with opposed band being provided with edge notches for registry with the notches of the leaves, and securing means extending through registering notches latter to the band.

13. A piston ring expander comprising a carrier band, a plurality of spring leaves overlying the band, the leaves being provided with opposed means operatively related to said band and extending through said notches and over the leaves for securing the latter to the band.

14; A piston ring expander adapted to be placed through a pair of apertures with the intermediate edge notches intermediate the ends thereof, the

and over the band and leaves for securing the edge notches intermediate the ends thereof, and

inapistonringgroovebehindapistonringand' comprising a thin. flexible carrier band. a plurality of independent circumferentially spaced spring leaves in overlying substantially concentric relation to said carrier band, and projections integral with said can'ier band at an edge thereof securing the central portion of said leaves to said carrier band, whereby the end portions of the leaves project in Opposite directions with respect to said projections and are free to engage the inner periphery of a piston ring.

15. A piston ring expander adapted to be placed in a piston ring groove behind a piston ring and comprising a thin, continuous carrier band, a plurality of spring leaves overlying and substantially concentric, with the carrier band, and spaced projections integral with the band at one edge thereof and disposed radially outwardly therefrom and securing the central portion of said leaves to said carrier band, said carrier band being provided adjacent the base of said projections with undercuts whereby said projections lie within the width of said carrier band.

16. A piston ring expander consisting of two functional parts, one of said parts being a thin, continuous, flexible carrier band and the other of said parts being a plurality of spring leaves in overlying, substantially concentric and circumferentialiy spaced relationship to said band, and means comprising projections integral with the band securing said leaves to said band intermediate the ends of said leaves.

17. A piston ring expander comprising at least,

two parts, one of said parts constituting a thin, continuous, flexible carrier band and the other a spring leaf, one of said parts being provided with a recess, said parts being arranged in substantially concentric relationship, and means securing said parts in said relationship, said means comprising an integral projection extending from the other of said parts through said recess and contacting with one face of the part having said recess.

18. A piston ring expander adapted to be placed in a piston ring groove behind a piston ring and edge notches intermediate the ends thereof and Q said carrier band being provided with edge notches in registry with theedge notches of said leaves; and anattaching through said notches and about said carrier band and leaves securing the mid-portion of said u leaves to said carrier band. 

